MDM2 and glioblastoma: Acetylation has been shown to extend p53 half‐life by inhibiting the E3 ligase MDM2 mediated ubiquitination and proteasomal degradation.[27, 28] However, no significant changes in p53 ubiquitination (Figure S3A, Supporting Information) and half‐life (Figure S3B, Supporting Information) were observed in GBM cells with Smad1 KO or OE.